Excessive data usage by Messaging App (International 3G/4G SIM card on AT&T and T-Mobile)
I use FP 3g/4g SIM card with unlocked phone (Samsung Galaxy Avant) that supports all 3g and 4g bands of AT&T and T-Mobile (if it is important). Data usage is relatively small (less than 250 MB per month), phone calls less than 100 mins per month. Suddenly I mentioned huge data usage for first 10 days of this billing cycle and main and only offender is Messaging App: 236 MB. How is it possible? Goofle Play auto updates are set to Wi-Fi only, so, it is not Messaging app update.